ER Basics for Rookies

Ask any seasoned emergency physician what separates a smooth intubation from a disaster, and you’ll often hear the same answer: preoxygenation. In critically ill patients, oxygen reserves are frighteningly limited, and a few seconds of apnea can mean profound desaturation. For rookies, learning effective preoxygenation techniques is one of the most important airway skills.

Why Preoxygenation Matters

• Extends the “safe apnea period.” Critically ill patients desaturate far faster than elective OR patients.
• Reduces peri-intubation hypoxemia, arrhythmias, and cardiac arrest.
• Buys you time for a controlled intubation rather than a crash scenario.

Remember: Intubation is an oxygenation procedure as much as it is an airway procedure.

The Physiology in a Nutshell

• Room air: PaO₂ ≈ 100 mmHg, oxygen reservoir minimal.
• 100% O₂ for 3–5 minutes: alveoli and blood “flooded” with oxygen, nitrogen washed out.
• More oxygen stored = longer until desaturation during apnea.

But critically ill patients (sepsis, ARDS, trauma, obesity) have shunt physiology, low FRC, and high metabolic demand, so their “safe apnea” may last seconds, not minutes.

Standard Preoxygenation Strategies

1. Non-Rebreather Mask (NRB)

• Simple, widely available.
• Delivers ~60–70% FiO₂ if sealed well.
• Better than nothing, but not ideal for severely hypoxemic patients.

Rookie pearl: Always crank the flow to 15 L/min (not 6–8). Anything less is ineffective.

2. Bag-Valve-Mask (BVM) with PEEP

• Provides higher FiO₂ (close to 100%).
• Adding PEEP valve (5–10 cm H₂O) improves alveolar recruitment.
• Requires a tight mask seal; ideally two-person technique (one holds mask with both hands, the other squeezes bag).

Rookie pearl: Even before paralysis, gentle BVM with PEEP during preoxygenation can stabilize sats in shunt physiology.

3. High-Flow Nasal Cannula (HFNC)

• Delivers heated, humidified oxygen up to 60 L/min.
• Provides both preoxygenation and apneic oxygenation after induction.
• Better tolerated in awake, dyspneic patients.
• Particularly useful in obesity and anticipated difficult intubation.

4. Non-Invasive Ventilation (NIV/BiPAP)

• Best choice for severe hypoxemia (PaO₂/FiO₂ < 150).
• Combines high FiO₂ + PEEP + pressure support to improve oxygenation before intubation.
• Evidence supports NIV preoxygenation in critically ill ED patients.

Rookie pearl: In crashing hypoxemic patients, NIV for even 1–2 minutes may improve sats enough to safely attempt RSI.

5. Apneic Oxygenation (Nasal Cannula During Intubation)

• Place nasal cannula (15 L/min) under the mask and keep it on during laryngoscopy.
• Provides continuous O₂ flow into the pharynx, extending apnea time.
• Evidence is mixed, but simple, cheap, and low-risk.

Optimizing Preoxygenation: Practical Steps

1. Position matters:
   • Use semi-Fowler (30° head-up) or ramped position in obese patients.
   • Improves FRC and reduces airway collapse.
2. Seal matters:
   • A poor mask seal = wasted effort. Always check for fogging or chest rise.
3. Time matters:
   • Aim for 3–5 minutes of preoxygenation if patient stability allows.
   • In peri-arrest patients, even 30–60 seconds of high-flow O₂ is better than nothing.
4. Adjuncts matter:
   • Oropharyngeal or nasopharyngeal airways improve preoxygenation in obtunded patients by preventing soft tissue collapse.

Common Rookie Mistakes

• Using NRB at low flow rates (“6 L/min NRB” is basically useless).
• Forgetting to add PEEP during BVM preoxygenation.
• Flat positioning in obese/hypoxemic patients—dramatically shortens safe apnea.
• Removing oxygen sources too early during intubation attempt.
• Not using apneic O₂ when available (nasal cannula can buy you precious seconds).

Strategy by Patient Type

Rookie Pearls

• Think: “Every second of preoxygenation = seconds of safety during apnea.”
• If sats are <90% after preoxygenation attempts, call it out: “This patient is high risk for peri-intubation desaturation—Plan B ready.”
• Always start RSI with oxygen already flowing (mask, cannula, or HFNC) before pushing drugs.

Take-Home Message

Preoxygenation is not a luxury—it’s the single most important protective step before RSI in the critically ill. Rookies should master the basic tools (NRB, BVM, nasal cannula) and become comfortable escalating to advanced methods (NIV, HFNC) when needed.

In emergency intubation:

• Position up
• Oxygen on
• PEEP in
• Nasal cannula running

That’s how you buy the safest possible intubation window.